Centaurea solstitialis
Centaurea solstitialis (Yellow Star Thistle), Centaurea solstitialis (Yellow Starthistle), Fact Sheet No. 1: Yellow Starthistle, Progress in Yellow Starthistle Biological Control, Yellow Starthistle, Yellow Starthistle (Centaurea solstitialis L.), Yellow Starthistle - UC Pest Management Guidelines, Yellow Starthistle Biology and Control, Yellow Starthistle Information
CalFlora: Centaurea calcitrapa
Common names: red or purple starthistle. Photographs and description, distribution map for California, classification as invasive species and noxious weed.
Centaurea calcitrapa
Red Star-Thistle. Detailed plant classification, national distribution maps, status as invasive plant and noxious weed. From the USDA PLANTS data base.
Centaurea tauromenitana
Image of plant, close-up of flower head.
Knapweed
Photographs, descriptions and distribution information for spotted knapweed (Centaurea maculosa), brown knapweed (Centaurea jacea) and Russian knapweed (Centaurea repens). From the Ontario Ministry of Agriculture and Food.
Purple Starthistle Identification
Identifying photographs for Centaurea calcitrapa. From King County, Washington, Department of Natural Resources.